from scipy.signal import butter, lfilter

if __name__ == '__main__':
    low = 15 * 2 / 50
    hi =  18 * 2 / 50
    b, a = butter(1, [low, hi], btype='bandpass', analog=False)
    data = [258,260,262,264,266,268,270,272,274,276,278,280,281,283,285,287,289,291,293,294,296,298,300,301,303]
    y = 1 * lfilter(b, a, data)
    print(y)